42 
[January, 
The Port of Ymuiden. 
beach, are 1312 yards distant from one another. Thence 
their directions converge, so as to make an angle of 
77 degrees with their base line, and at 1312 yards from the 
shore they are 721J yards apart. From this point they 
begin to converge more rapidly, so that, with an additional 
length of 377 yards, — making 1689 yards in total length, 
— they terminate 284 yards apart at the harbour mouth. 
The piers consist of a solid sea wall, 27 feet wide at top, and 
increasing in thickness downwards by one-seventh of their 
height. They are formed asfollows : — First of all a foundation 
of basalt rock was thrown into the sea, about 40 yards wide and 
1 yard in thickness. On this a superstructure is raised, formed 
of concrete blocks, varying from 4 to 10 tons in weight. The 
rabble foundation was levelled by divers, by whom also the 
blocks below low water were fitted, without any cement in their 
joints, the blocks being let down to their site by a powerful 
steam crane called a “ Titan.” From low water the blocks 
are laid in cement ; for the lowest joints— which are only a 
few hours above water — a quick-setting Medina cement was 
used, and for the higher joints Portland cement. The top 
of the piers is generally 13 feet 6 inches above the Amster- 
dam pile (datum). The parapet on the top of each pier 
consists entirely of concrete, moulded on the spot in frames 
ereCted in situ. Behind this is a pavement of brick in 
cement, supported by a band of granite along the inner top 
line. In the construction of each of the two piers there 
has been used 433,600 yards of concrete blocks, 77,700 tons 
of cement, 229,000 cubic yards of shingle, 130,900 cubic 
yards of basalt, and 19,035 cubic yards of broken bricks, 
the last-named being used in the formation of the concrete 
blocks placed in the middle of each pier. 
In order to afford further protection to the piers against the 
force of the waves, a slope of rubble rock has been thrown into 
the sea on the outside of each pier, the lower blocks of these 
wave-breakers being 10 tons each in weight, and those 
above low water about 20 tons each. The harbour will 
afford berths for three hundred large vessels. 
The canal, in passing from the harbour through the 
downs, runs eastward at first in the direction of an arc of a 
circle, with the concave side turned southwards, for a dis- 
tance of 1300 yards, at the end of which are the North Sea 
locks. The curved form of the canal in this portion serves 
principally to protect the locks from the force of the waves. 
From this point the canal runs for some distance in a 
straight line, and afterwards sometimes in curves, with occa- 
sional straight reaches, to Amsterdam—a total distance of 
25,919 yards. 
